1. Field of the Invention
The present invention relates to a power output apparatus, a vehicle equipped with the power output apparatus, and a control method of the power output apparatus.
2. Description of the Prior Art
One proposed power output apparatus to be mounted on a vehicle has an engine with in-cylinder fuel injection valves for injecting the fuel into cylinders and a toroidal continuously variable transmission (see, for example, Japanese Patent Laid-Open Gazette No. 2000-52817). This power output apparatus sets a target torque of the engine and a target input shaft rotation speed of the transmission, based on the driving state of the vehicle and a target driving force that varies with a variation in driving state. The target torque of the engine and the target input shaft rotation speed of the transmission vary according to the state of combustion, which reflects a variation in air-fuel ratio of the air-fuel mixture supplied to the engine. The engine and the continuously variable transmission are controlled with allocation of a driving force defined by the target torque of the engine and the target input shaft rotation speed of the transmission. Such control aims to drive the engine under the operating conditions of the optimum fuel consumption.
Another proposed power output apparatus has an engine with both in-cylinder fuel injection valves for injecting the fuel into cylinders and port fuel injection valves for injecting the fuel in an intake port (see, for example, Japanese Patent Laid-Open Gazette No. 2001-20837). This proposed power output apparatus sets 0 to a share of fuel injection from the port fuel injection valves in a stratification range and increases the share of fuel injection from the port fuel injection valves in a homogeneous range with an increase in rotation speed of the engine and with an increase in engine loading. Such control aims to enhance the combustion performance in the stratification range and to attain the appropriate combustion performance in the homogeneous range.